Chap. IX.] 



FORE AND HIND LIMBS. 



tibia and fibula the (a) hand (maims) is divi- 

 sible into wrist (carpus), palrn (metacarpus), and 

 digits ; the (0) foot (pes), into tarsus, metatar- 

 sus, and digits. The digits are typically five in. 

 number, and consist of a number of separate pieces, 

 articulated on one another ; the number of these 

 phalanges is inconstant, but, as we ascend the 



Am 



Fig. 147. Side View of the Pelvis of an Adult Fowl. 



I?, Ilium; is, ischium ; Pb, pubis; dl, dorsal vertebrae; cd, caudal vertebras; 

 AW, acetahulum. (After W. K. Parker.) 



series, we observe a reduction ; they are sometimes, 

 though not always, provided with horny claws. 



The humerus, which fits, by its anterior rounded 

 head, into the glenoid cavity formed by the edges of 

 the scapula and coracoid, acquires a greater freedom 

 of movement when, as in the Mammalia, the coracoid 

 is reduced in extent. It is generally characterised 

 by the possession of a more or less strong bony ridge 

 to which the deltoid muscle is inserted, the size of 

 which is, of course, in proportion to the use to which 

 the fore limb is put ; and the ridge, therefore, is very 

 pronounced in fossorial and flying forms. In the 

 Carinatse the muscle that elevates the wing lies, with 

 those that depress it, in the pit formed by the sides of 

 the keel of the sternum, and its tendon passes over 



